When a jet-powered aircraft lands, the landing gear brakes and aerodynamic drag (e.g., flaps, spoilers, etc.) of the aircraft may not, in certain situations, be sufficient to slow the aircraft down in the required amount of runway distance. Thus, jet engines on most aircraft include thrust reversers to enhance the braking of the aircraft. When deployed, a thrust reverser redirects the rearward thrust of the jet engine to a generally or partially forward direction to decelerate the aircraft. Because at least some of the jet thrust is directed forward, the jet thrust also slows down the aircraft upon landing.
Various thrust reverser designs are commonly known, and the particular design utilized depends, at least in part, on the engine manufacturer, the engine configuration, and the propulsion technology being used. Thrust reverser designs used most prominently with jet engines fall into three general categories: (1) cascade-type thrust reversers; (2) target-type thrust reversers; and (3) pivot door thrust reversers. Each of these designs employs a different type of moveable thrust reverser component to change the direction of the jet thrust.
Cascade-type thrust reversers are can be used on high-bypass ratio jet engines. This type of thrust reverser is located on the circumference of the engine's midsection and, when deployed, exposes and redirects air flow through a plurality of cascade vanes. The moveable thrust reverser components in the cascade design includes several translating sleeves or cowls (“transcowls”) that are deployed to expose the cascade vanes.
Target-type reversers, also referred to as clamshell reversers, are typically used with low-bypass ratio jet engines. Target-type thrust reversers use two doors as the moveable thrust reverser components to block the entire jet thrust coming from the rear of the engine. These doors are mounted on the aft portion of the engine and may form the rear part of the engine nacelle.
Pivot door thrust reversers may utilize four doors on the engine nacelle as the moveable thrust reverser components. In the deployed position, these doors extend outwardly from the nacelle to redirect the jet thrust.
The primary use of thrust reversers is, as noted above, to enhance the braking of the aircraft, thereby shortening the stopping distance during landing.
Hence, thrust reversers are usually deployed during the landing process to slow the aircraft. Thereafter, when the thrust reversers are no longer needed, they are returned to their original, or stowed, position and are locked.
Each of the above-described thrust reverser system designs may include one or more locks to inhibit unintended thrust reverser movement and/or the actuators that move the thrust reversers. Some types of locks are configured such that power is supplied to a lock to disengage it, to allow actuator and/or thrust reverser movement. Conversely, when power is removed from the lock, it is engaged to prevent actuator and/or thrust reverser movement. In some designs, the locks will engage and prevent actuator and/or thrust reverser movement when power is removed, no matter what the position may be of the thrust reverser. In other designs, if power is removed from the lock when the actuator is in either the stowed or deployed position, the locks will engage and prevent actuator or thrust reverser movement. Hence, in either of these designs, if power is inadvertently lost to the lock while the thrust reversers are not in the stowed position, then further movement of the thrust reversers may be prevented. However, despite this drawback, thrust reverser lock systems are safe, reliable, and robustly designed.
Hence, there is a need for a lock assembly for a thrust reverser system that does not prevent thrust reverser movement when the thrust reversers are out of the stowed position and the lock assembly is in the locked position. The present invention addresses this need.